Mukund invests a sum of ₹5400 and Sachin invests a sum of ₹9400 at the same rate of simple interest per annum. If, at the end of 5 years, Sachin gets ₹960 more interest than Mukund, then find the rate of interest per annum (in percentage).

Find the simple interest (in ₹) on ₹2000 as a sum borrowed at 7% per year rate of interest for 4 years.

Find the simple interest (in ₹) on ₹3000 as a sum borrowed at 8% per year rate of interest for 5 years.